ebs gp3 - read throughput sudden increase

Based on the information provided, it appears that your EBS gp3 volume experienced a sudden increase in read throughput, accompanied by a CPU spike and high I/O wait times. This situation could be caused by several factors:

1. Micro-bursting: EBS volumes can experience micro-bursting, where there are short periods of high IOPS or throughput that may not be captured by standard monitoring tools. This could explain the sudden spike in read throughput.

2. Lazy loading: If the instance was recently restored from a snapshot or if there was a period of inactivity, the EBS volume might be experiencing lazy loading. This occurs when data is being read from the volume for the first time since restoration, causing increased read activity.

3. Background processes: Although you mentioned that you didn't see any unusual processes, there might be background system processes or scheduled tasks that caused the spike in read activity. These could include system updates, log rotations, or database maintenance tasks.

4. Throttling: The sudden increase in throughput could be due to the volume catching up after a period of throttling. If the volume was previously throttled due to reaching its IOPS or throughput limits, it might show a spike when the throttling is lifted.

5. Application behavior: An application running on the instance might have triggered a large read operation, such as a database query scanning a large table or a file system operation reading many small files.

The fact that the server experienced downtime from 6:47 AM to 8:25 AM, followed by high load average, suggests that there might have been a more significant issue affecting the instance. This could be related to the EBS volume performance, but it could also be due to other factors such as network issues, resource contention, or application problems.

To further investigate and prevent future occurrences:

1. Enable Enhanced Monitoring with a 1-second granularity to capture micro-bursting events.
2. Review application logs for any unusual activity during the affected time period.
3. Check for any scheduled maintenance or backup tasks that might have triggered the high read throughput.
4. Monitor the EBS volume's IOPS and throughput utilization to ensure it's not consistently reaching its limits.
5. Consider increasing the provisioned IOPS or throughput for the gp3 volume if the workload consistently requires higher performance.

If the issue persists or you need more detailed analysis, it would be advisable to contact AWS Support for further assistance.
Sources
Troubleshoot latency of EBS volumes in an RDS instance | AWS re:Post
Amazon EBS General Purpose Volumes - Amazon Web Services